SEOUL (Yonhap) -- North Korea's military threatened on Nov. 12 to restrict overland passage across the border with South Korea in a critical move likely to further damage already frayed ties between the two neighbors.

The North will "strictly restrict and cut off" the passages through the military demarcation line starting Dec. 1, the North's military said in a statement read over the telephone to South Korean military authorities.

In a separate statement made later, the North's Red Cross said it will close a liaison office in the truce village of Panmunjom and withdraw its representatives there. It also said it will sever all cross-border phone channels with its South Korean counterparts.

In yet another blow, the North's Foreign Ministry issued a statement same day that it would not permit nuclear sampling to its partners in the six-party denuclearization talks to verify its nuclear declaration. It said the North has never agreed on sampling, claiming the verification will be limited to inspectors' access to the site, document confirmation and interviews with engineers.

In its threat to close the border, the North's Korean People's Army said: "The racket of confrontation with the DPRK kicked up by the South Korean puppet authorities is going beyond the danger level despite its repeated warnings," according to a report carried by Pyongyang's official Korean Central News Agency (KCNA).

DPRK stands for the Democratic People's Republic of Korea, the official name of North Korea.

The warnings came as Pyongyang has grown increasingly vocal over South Korean civic groups' flying of propaganda leaflets over the border via balloon.

The North indicated the restriction is only the beginning of a spate of retaliatory measures that could ultimately lead to the complete severing of inter-Korean relations. Seoul "should never forget that the present inter-Korean relations are at the crucial crossroads of existence and total severance," the statement said.

The message was officially issued by Lt. Gen. Kim Yong-chol, the North's top delegate to the inter-Korean general-level military talks. Kim communicated that he was speaking on behalf of unspecified high-level authorities, likely North Korea's all-powerful National Defense Commission.

"The South Korean puppet authorities' unchanged position and attitude towards the historic two declarations have been finally confirmed," Kim said, referring to what he called Seoul's denial of agreements reached during the inter-Korean summits of 2000 and 2007.

The North's Red Cross Society statement particularly criticized Seoul's recent participation as a sponsor of a U.S. resolution on North Korea's human rights abuses. The statement called Seoul's active role in drawing the U.N. human rights resolution a "blatant challenge" to the dignity and system of North Korea and a "total negation" of agreements signed in historic summits between the leaders of the two Koreas in 2000 and 2007.

"It is absolutely (an) intolerable, treacherous and anti-reunification act for the group of traitors to have brought somebody's non-existent 'human rights' issue even to the international arena, daring to blatantly challenge the DPRK's dignity and system," said the statement, according to the KCNA.

The statement said the closure of the Red Cross channel will lead to a full suspension of humanitarian programs that arrange temporary reunions of family members who have been separated by the inter-Korean border since the 1950-53 Korean War.

Lee will have to assume responsibility for the deteriorated cross-border ties, it said, adding that the fate of inter-Korean relations will depend on Seoul's future attitude.

Related to the latest announcement made by the socialist country, South Korea issued a statement expressing regret over steps that could affect cross-border relations, and said any differences should be resolved through direct dialogue.

The Unification Ministry said Seoul does not want deterioration of bilateral relations and added that all past agreements between the two Koreas will be respected.

Seoul's Unification Ministry spokesman, Kim Ho-nyoun, said in a statement," If the North carries out such measures, it will have a negative impact on efforts to improve inter-Korean relations." The spokesman reiterated, however, that Seoul remains hopeful that North Korea will return to dialogue with Seoul.

Hundreds of South Koreans cross the border every day for business or tourism purposes, despite chilled relations. Tightened border control would negatively impact cooperative efforts at the Kaesong joint industrial complex just north of the demilitarized zone near the west coast, officials said.

More than 35,000 North Koreans are employed by 83 South Korean manufacturers at the Kaesong complex, a symbol of inter-Korean peace and cooperation.

Pyongyang has repeatedly threatened to take retaliatory measures, which could include shutting down the inter-Korean industrial park, unless Seoul prevents civic groups from flying balloons carrying leaflets.

The North has called the leaflets -- which reportedly elaborate on North Korean leader Kim Jong-il's luxurious private life as well as rumors on his illness -- an unpardonable challenge to the North's "supreme sovereignty." U.S. and South Korean intelligence officials have said the 66-year-old North Korean leader suffered a stroke in August. The North has vehemently denied those reports.

South Korean civic groups, many of whose members are North Korean defectors, have continued to send leaflets despite Pyongyang's threats and requests from Seoul to halt their activities.

On Nov. 6, a delegation from the North's National Defense Commission inspected the Kaesong complex in an apparent attempt to pressure Seoul into making concessions.

The North Korean officials reportedly asked the managers of South Korean firms operating in Kaesong how long it would take for them to fully withdraw.

Pyongyang has called on Seoul to observe the two summit agreements, which include the creation of dozens of new cross-border economic cooperation projects, though Seoul insists it has never not observed them.

Political relations between the two Koreas have been strained since the conservative South Korean President Lee Myung-bak took office in late February, pledging to link inter-Korean relations to the North's nuclear disarmament.

Meanwhile, South Korea's presidential office, Cheong Wa Dae, expressed regret over the North Korean military's abrupt decision to close the inter-Korean border next month.